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How to code-sign OS X Electron apps in Travis CI

This blog post assumes you already generated your *.p12 certificate. If not, please refer to any of the plenty awesome tutorials out there.

Accessing the certificate from Travis CI

Travis CI doesn’t have a feature to securely upload files that will be accessible within the build.

As a workaround, we can base64 encode our *.p12 file and store it as a secure environment variable from our project’s settings section. During the build, we can decode the environment variable and normaly access our certificate file.

We can perform the encoding by running the following command:

base64 path/to/certificate.p12

If your certificate is password-protected, you might want to store the password as well.

Travis CI secure environment variables

Later, we can decode by piping the contents of the environment variable to base64 --decode:

echo $CERTIFICATE_OSX_P12 | base64 --decode > certificate.p12

Importing the certificate to the Keychain

Now that we know how access our certificate from a Travis CI build, the next step is to import it to the Keychain in order to use with codesign.

In order to get code-signing to work on Travis CI, we need to explicitly unlock the Keychain before being to able to make use of the certificates it contains.

Sadly we don’t have the Travis CI System Keychain password to perform the unlocking, so we’ll create a new Keychain, set it as default, and unlock it ourselves using the handy security command line tool:

security create-keychain -p mysecretpassword build.keychain
security default-keychain -s build.keychain
security unlock-keychain -p mysecretpassword build.keychain

We can finally import our certificate to our new Keychain with the following command:

security import certificate.p12 -k build.keychain -P <certificate password, if any> -T /usr/bin/codesign

You can ensure the certificate was added correctly with the following command:

security find-identity -v

Which should output something like:

1) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX “Developer ID Application: John Doe (XXXXXXXXXX)”
    1 valid identities found

Code-signing the application

Now that everything is setup, we can pass our sign identity to electron-packager and electron-builder.

Alternatively, you can use the lower level electron-osx-sign package, or even use codesign yourself:

codesign --deep --force --verbose --sign "<identity>" Application.app

Here’s an example script you can use in your .travis.yml deploy section:

if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
  export CERTIFICATE_P12=Certificate.p12;
  echo $CERTIFICATE_OSX_P12 | base64 — decode > $CERTIFICATE_P12;
  export KEYCHAIN=build.keychain;
  security create-keychain -p mysecretpassword $KEYCHAIN;
  security default-keychain -s $KEYCHAIN;
  security unlock-keychain -p mysecretpassword $KEYCHAIN;
  security import $CERTIFICATE_P12 -k $KEYCHAIN -P $CERTIFICATE_PASSWORD -T /usr/bin/codesign;

  make deploy-or-whatever;
fi